Adding numbers using button to a textbox

Question

I'm new to programming and I have a problem. I have two buttons and a textbox. When I press the button, a number will show on the textbox, but when I press the second button the number in the textbox overwrites it and replaces it instead of adding to it in the textbox. How do I fix this? I want the values to add instead of replacing it.

public partial class Form1 : Form
{
    int value1 = 0;
    int value2 = 0;
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        value1++;
        textBox1.Text = value1.ToString();
    }

    private void button2_Click(object sender, EventArgs e)
    {
        value2 += 2;
        textBox1.Text = value2.ToString();
    }
}

}

textBox1.Text = (int.Parse(textBox1.Text) + value2).ToString(); — Dmitrii Bychenko
– Dmitrii Bychenko, Commented Dec 11, 2017 at 20:47

Dmitrii Bychenko · Accepted Answer · 2021-07-06 15:03:14Z

4

If you want to add two integers and assign the result back to textBox1 you have to

Parse textBox1.Text to integer: int.Parse(textBox1.Text)
Sum up values: int.Parse(textBox1.Text) + value2
Convert the outcome back to string: (...).ToString()

Implementation:

private void button2_Click(object sender, EventArgs e) { 
  value2 += 2;

  textBox1.Text = (int.Parse(textBox1.Text) + value2).ToString();
}

Edit: If there's a possibility that textBox1.Text doesn't contain a valid integer value (say, textBox1.Text is empty) you can use int.TryParse:

private void button2_Click(object sender, EventArgs e) { 
  if (int.TryParse(textBox1.Text, out var v)) {
    value2 += 2;
    textBox1.Text = (v + value2).ToString();
  }
  else {
    //TODO: textBox1.Text is not a valid integer; put relevant code here 
  } 
}

edited Jul 6, 2021 at 15:03

answered Dec 11, 2017 at 20:52

Dmitrii Bychenko

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Comments

redsoxfantom · Accepted Answer · 2017-12-11 20:50:06Z

0

You're using two separate variables (value1 and value2 above) to store the results of each button click, depending in which button was clicked. Think of it like this:

On program start:
value1 = 0
value2 = 0

User clicks button 1, which executes button1_Click. This increments value1 (via value1++), so the two variables look like this:

value1 = 1
value2 = 0

User then clicks button 2, which executes button2_Click. This sets value2 to whatever was previously in value2 + 2. However, note that the value of value1 is unchanged:

value1 = 1
value2 = 2

By having separate variables, each button click is operating on a different value. I would modify your code so there is only one value variable that both _Click functions modify.

answered Dec 11, 2017 at 20:50

redsoxfantom

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1 Comment

littlerufe Over a year ago

this gives an alternate idea for how to store the value, but does not answer the question about how to add the value to the text property of the text box...

whatthefish · Accepted Answer · 2017-12-11 20:58:49Z

0

Add this line:

textBox1.Text = (int.parseInt(textBox1.Text) + value2).toString();

after

value2 += 2;

into your button2_click method:

answered Dec 11, 2017 at 20:58

whatthefish

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